Submission #47711

#	Time	Username	Problem	Language	Result	Execution time	Memory
47711		fefe	Split the sequence (APIO14_sequence)	C++17	100 / 100	517 ms	83272 KiB

sequence

#include<bits/stdc++.h>
#include<inttypes.h>
#define MAX_N 100005
#define MAX_K 205
#define pb push_back
#define sq(x) ((x)*(x))
#define abs(x) ((x)>0?(x):(-(x)))
#define LL_inf (1LL<<60)
#define full_inf 0x7fffffff
#define half_inf 0x3fffffff
using namespace std;
typedef long long LL;
typedef pair<int,int> pii;
typedef pair<LL,LL> pil;
typedef long double LD;
struct node{
	LL fi,se,from;
};
LL n,k,l,r,ans,ansi,anss[MAX_K];
LL sum[MAX_N],t[3][MAX_N];
int From[MAX_K][MAX_N];
node line[MAX_N];
bool is_ok(node p1,node p2,node p3){return ((p1.fi-p2.fi)*(p3.se-p1.se))<=((p1.fi-p3.fi)*(p2.se-p1.se));}
int main(){
	LL i,j,x,y;
	node p;
	scanf("%lld %lld",&n,&k);
	for(i=1;i<=n;i++){
		scanf("%lld",&x);
		sum[i]=sum[i-1]+x;
	}
	for(i=1;i<n;i++)	t[1][i]=sum[i]*(sum[n]-sum[i]);
	ans=-LL_inf;
	if(k==1){
		for(i=1;i<n;i++){
			if(ans<t[1][i]){
				ansi=i;
				ans=t[1][i];
			}
		}
		return !printf("%lld\n%lld\n",ans,ansi);
	}
	for(i=2;i<=k;i++){
		l=r=0;
		line[r++]={sum[i-1],t[1-(i%2)][i-1],i-1};
		for(j=i;j<=n;j++){
			x=sum[j]-sum[n];
			t[i%2][j]=-LL_inf;
			while(r-l>1 && line[l].fi*x+line[l].se<=line[l+1].fi*x+line[l+1].se)	l++;
			if(r-l){
				y=line[l].fi*x+line[l].se+sum[j]*(-x);
				if(t[i%2][j]<y){
					t[i%2][j]=y;
					From[i][j]=line[l].from;
				}
			}
			y=t[1-(i%2)][j-1]+(sum[j]-sum[j-1])*(-x);
			if(t[i%2][j]<y){
				t[i%2][j]=y;
				From[i][j]=j-1;
			}
			p={sum[j],t[1-(i%2)][j],j};
			while(r-l>1 && is_ok(line[r-2],line[r-1],p))	r--;
			line[r++]=p;
			if(i==k && ans<t[i%2][j]){ans=t[i%2][j];ansi=j;}
		}
	}
	printf("%lld\n",ans);
	i=k;
	while(i){
		anss[i]=ansi;
		ansi=From[i][ansi];
		i--;
	}
	for(i=1;i<=k;i++)	printf("%lld ",anss[i]);	
	printf("\n");
	return 0;
}

Compilation message (stderr)

sequence.cpp: In function 'int main()':
sequence.cpp:27:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%lld %lld",&n,&k);
  ~~~~~^~~~~~~~~~~~~~~~~~~
sequence.cpp:29:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%lld",&x);
   ~~~~~^~~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 11 / 11
• Subtask 3: 11 / 11
• Subtask 4: 17 / 17
• Subtask 5: 21 / 21
• Subtask 6: 29 / 29